This guy is my main special sweeper. With a choice specs on an already massive special attack stat, Chandelure can rip enormous holes in the opponent's team. Fire blast and Shadow ball are the standard dual-STABs, Energy ball hits water types that would otherwise wall Chandelure, and HP fighting can get a bit of damage if I predict a switch into Blissey or Heatran. Chandelure's semi-low speed means I take Timid nature to outspeed other base 80 pokemon. With Thunder wave support from Latias, Chandelure can outpseed a significant portion of the meta-game. 3 immunities also give me many chances to switch in, but a weakness to stealth rock means I won't be bringing out this guy until late game.

Standard subpunching Breloom. I can switch into a slow, non-threatening pokemon like Ferrothorn or Blissey, use Spore, and Substitute on the switch. From there, I'll probably be spamming the Focus punch button. Adamant gives Focus punch maximum power at the cost of speed. Unfortunately, Breloom's defenses aren't that great, so I stray away from switching into any source of damage. Sometimes, I may paralyze opposing threats with Latias. Unfortunately, this prevents Breloom from inducing sleep, but it allows him to set up a substitute before the opponent and maybe still get a hit in.

Latias is my fast support/special wall. Her several resistances allow her many chances to switch in and paralyze something with Thunder wave. Wish and Protect let me heal other teammates or stall out special attackers. Dragon pulse and a Modest nature gives Latias some striking power, enough to OHKO a Gengar with some previous damage. If a grass type like Venusaur comes in to threaten Gastrodon, Latias will be my go-to solution. Unfortunately, I really don't have much on my team to take a Shadow ball or Dark pulse that would be aimed at Latias. My best bet would be to switch into Gastrodon.

Skarmory is my physical wall. Steel/Flying is an awesome typing, and its weaknesses can be sufficiently negated with Chandelure or Gastrodon. Stealth rock and Whirlwind can help me rack up a bit of damage, allowing for a clean sweep by one of my attackers. Careful allows me a bit of a buffer to Draco meteor. 28 Speed EVs allows me to outspeed opposing Skarmory and maybe get in Stealth rock or Roost before I get taunted.

Gastrodon is my specially oriented tank. His typing enables him to check an extremely large number of threats to my team, including Starmie and Rotom-W. Protect helps me scout for the random HP grass on pokemon such as Politoed. Scald is my standard water STAB, and its burn can help soften physical hits as well. HP electric might seem a bit weird, but it allows me to damage many of the threats Gastrodon is intended to counter, such as opposing bulky waters. Even if I get tricked a choice specs, Gastrodon has a high enough base special attack to become a pseudo-special attacker.

Threats:
While I haven't been able to go against everything in the OU meta-game, I have a good idea of what my team is strong against, and what it is weak against. The shaky specially defensive core of Gastrodon and Latias does have some weaknesses, with the most common one most likely being Gengar. Shadow ball is a real pain, and I may end up having to sack something to give my Landorus a safe switch in. My team also doesn't have much against stall teams, since nothing has rapid spin or any boosting move. Another significant problem is my weakness to ice. Latias, Landorus, and Breloom are all weak to ice, and my only resistance is in the frail Chandelure, which doesn't help.

This is actually a pretty good team for a beginner, so good job. Calm Mind Reuniclus and Substitute + Calm Mind Jirachi seem like major threats to the team. The former sets-up on a Choice-locked Chandelure and Landorus on an ineffective move, or even on Latias, not caring about Paralysis, and even Gastrodon who can't do much against itand hitting your team hard with boosted Psychic / Focus Blast. Jirachi sets-ups on the same threats under rain and get up a substitute and acquire multiple CM boosts, your best bet at breaking the subs is Landorus's Earthquake, who goes down to boosted Water Pulse.

What I'd suggest is trying a Calm Mind + Roar set on Latias to mitigate your weakness to Calm Mind Reuniclus. Currently, your Latias is set-up bait for Reuniclus and other threats who aren't speed dependent. You already have a solid special sponge in Gastrodon and making Latias function the same way brings redundancy to the team. CM + Roar can set-up alongside Reuniclus, and Roar it out to erase its boosts, and also discouraging other Pokemon from setting-up with Roar. It's also a better answer to Calm Mind Keldeo for the same reason, as currently you have to rely on Thunder Wave to paralyze it and then finding the opportunity to bring in Breloom or Skarmory to outspeed and KO, while both risk getting hit hard by a boosted HP Ice or Hydro Pump. The spread is the same as you have now but with Calm Mind over Wish, Recover over Protect, and Roar over Thunder Wave, with a Timid Nature to outspeed Gengar and tie with Latios. If you really want to keep the paralysis support for Chandelure, then at the very least you should try Roar over Wish and Recover over Protect, to simply force out Reuniclus and Keldeo from setting up on you, while keeping a reliable recovery move.

For Calm Mind Jirachi, a simple yet effective change would be to try Earthquake over Hidden Power Electric with a Sassy nature, as to not hamper its power. With Earthquake, you're able to break its Substitutes, and since you already resist its coverage moves most of the time, it won't be able to do much against you, and be forced to switch. Hidden Power Electric only really hits Starmie, who is already hard-pressed to do anything to Gastrodon, and Gyarados too, but Skarmory can pHaze that out. Ice Beam or Toxic over Protect are also good options, preventing Dragon- types such as Dragonite or even Latios and Latias from coming in for free and launching powerful attacks / set-up for boosts.

Lastly, maybe you want to try a Bulk Up set on Breloom, as breaking through more defensive teams isn't the easiest task for your team (especially Rain-Stall, where Chandelure will get nerfed). With a Bulk Up set, you're able to set-up on things like Gliscor (lacking Acrobatics), Rotom-W (whose Hydro Pumps otherwise have a shot of 2HKOing your current Breloom), and Tentacruel easier, the former two you'd want to remove to have an easier time if you want to sweep with Landorus. Breloom + Latias also handle each other's threats, allowing the other to sweep. Again, it's optional, and may be worth a test,

yeah i agree with afterburn, when i saw "my first team" i was expecting a bunch of NUs, so well done.

You have protect for scouting on latias and gastrodon, both of them would like that moveslot for something else. CM latias is bulky and has can sweep on its own, which is really useful.

Subpunch loom is great, extremely annoying and quite capable of taking out a few pokes, but it doesn't exactly sweep. I'd either use a bulk up set like afterburn suggested, or life orb sword dance techniloom.

About your ice weakness, ice is a bad defensive typing (weak to sr) so there aren't many ice types in ou. Mamoswine is fairly common, but dealt with by skarm. Hp ice, ice beam as a coverage move is fairly common though, but i think gastro can take most of those.

Speaking of ice as coverage, you should try ice beam on gastrodon for dragons.

toxic/recover/scald/EQ/ice beam are all good options for gastro, so I would try using a combination of those.

Timid on latias is important to use its great speed.

If you could fit starmie on, maybe over gastro (although I'm not sure about getting rid of gastro) it would give you rapid spin and an ice resist. On the other hand, it leaves you with another dark/ghost weakness so maybe tentacruel would be better, however outside of rain on an offensiveish team tenta isn't that great.

Your team looks solid, you can handle most of the OU threats. Combination like Gastrodon + Skarmory or Latias + Landorus are pretty effective against rain and sandstorm teams. Your main sweeper Chandelure is fun to play but not very effective in this role. Well, let's make an analysis of the team !

Firstly, the major porblem I saw when I cliked on your RMT was Chandelure. I know this pokemon can be very annoying but the choice specs set is easily walled by so many pokemons and even by sweep teams. Chandelure's speed is not enough high to make of this pokemon decent choice spec sweeper. Chandelure is also very weak to stealth rocks if doesn't have pain split and even more if you don't have a rapid spinner. It's why I think that you should remove this pokemon. A specially defensive Heatran would be a great argument for your team. Heatran will work pretty well in your team, you can put stealth rocks on it set spikes to skarmory. You will have a decent combination of spikes + Stealth rock, a great defensive core with Heatran + Latias and a good check to SubcalmMind Jirachi which can be very annoying for your team. A specially defensive set is used over a physically defensive set because Lava Plume's high burn rate enables Heatran to shrug off physical hits most of the time. Here is standard specially defensive Heatran if you want to try it:

Then, I don't like so much the using of sub puncher Breelom. This pokemon could be helpfull in a rain team BW1, but I find it pretty useless in BW2. There are to many pokemon able to deal with it, and the drop of stall teams in the metagame have made of this breelom a to weak pokemon for a team like yours. Toxic spikes are certainly the biggest threats of the team and breelom can't remove it. It's why I suggest you to replace your Breelom by a specially defensive Amoonguss. This pokemon has a good synergie with the other pokemons and don't really need to be accompanied with a rapid spinner. Spore can easily turns the game back in your favor while Clear Smog can halt threatening setup sweepers in their tracks. The EV spread brings out the best in Amoonguss's defensive capabilities. Black Sludge and a Bold nature further augment Amoonguss's decent special bulk which allows you to take most of the special of the metagame excepted Hurricane and Fire Blast. I suggest you to use this Amooguss if you want to try my suggestions:

Now that you have a decent combination of SR + Spikes and what to wall easily water and electric type moves, I think that your team don't need Gastrodon anymore but an Anti-spinner. There are not many anti spinners reliable in OU. It's why I suggest you to use a Physically defensive jellicent instead of your Gastrodon. Jellicent's typing is arguably its most endearing quality, and allows it to be a fabulous switch-in to a variety of threats. This set works well for teams that need a reliable spinblocker, as Jellicent can take most of them on with relative ease. Use the standard the standard set with a bold nature if you want to have a better staying power. Cursed Body has more situational uses, but it's better for your team because you don't have any counter to calm minder Reuniclus. Water absorb is still viable but you already have Amoonguss to check Keldeo. If you want to test it :